The objective of this proposal is to test Jerne's (1974) auto-regulatory mechanism of the immune response based on his idiotype-anti-idiotype network theory. Restricted anti-hapten antibody responses in mice to 4-azophthalate and DNP, and a homogeneous, IgM, anti-dextran response, with which we have experience, provide excellent systems to unequivocally test this theory of immune response control. Assuming that auto-anti-idiotype clones are immunocompetent cells possessing on their membrane, receptors specific for antihapten and anti-dextran antibody combining sites, we have designed experiments to remove these cell clones (1) by selective exposure to radiation, (2) by affinity chromatography, and (3) by immunocytoadherence. After removal of the auto-anti-idiotypic control the depleted cell population will be examined to see if it can mount a greater immune response to the relevant antigen. The clones involved in the immune response will be characterized by focusing the antibody molecules in analytical isoelectric focusing and by amino acid sequencing of the molecules. The auto-anti-idiotypic cell clones that were removed by affinity chromatography or by immunocytoadherence will be recovered and examined for their ability to suppress all immune response to the relevant hapten. In order to be able to make these determinations the investigation should be done with antihapten antibody which is homogeneous or of restricted heterogeneity. Therefore, we will be looking for additional means of preparing homogeneous antibody. Homogeneous responses have been developed to homogeneous antigens prepared by coupling haptens to unique residues on carrier molecules and we have had success with mono-DNP-insulin. We propose to use mono-substituted cobra neurotoxins to obtain large amounts of homogeneous antihapten antibodies. The mono-substituted toxins should make better antigens because they have a compact, rigid structure like gramicidin S. The toxins provide several single residues in their structure, tryptophan, tyrosine and histidine, to which haptens can be easily coupled and where they can be presented in a single environment on the surface of the rigid carrier.